This invention relates to methods for treatment of glaucoma by use of a laser to create a perforation in the sclera.
Glaucoma is a potentially debilitating disease of the eye in which the intraocular pressure of fluid within the eye rises above normal levels. Glaucoma is generally treated by a surgical procedure where a small hole is introduced through the sclera, which is the outer coating of the eye, to allow fluid within the eye to drain into the subconjunctival space, between the conjunctiva and the sclera. Laser light has been used to create such a hole. For example, in 1969 L'Esperance increased absorption of the sclera in the visible region by injection of Indian ink, to allow use of a continuous wave argon ion laser to create a scleral hole. L'Esperance "Laser Trabeculosclerostomy in Ophthalmic Lasers: Photocoagulation, Photoradiation, and Surgery." St. Louis: C. V. Mosby Co., 538-543, 1969. In addition, Latina et al. describe the development of an ab interno laser sclerostomy using a gonio lens technique. Latina et al. ARVO Abstract, p. 254, No. 12, 1986. Methylene blue was applied iontophoretically to the sclera and the sclera then ablated by use of one microsecond long dye-laser pulses at 660 nanometers delivered through a 600 micron optical fiber. Ablation was observed at 50 milliJoules (mJ) per pulse. The authors state that the "potential of this technique for clinical use is being investigated." In 1987, Latina et al., ARVO, No. 11, described ab-interno scleral ablations using one microsecond long pulses at energies of between 30 and 40 mJ per pulse. They state that the method utilizes visible radiation "which offers the potential for developing a minimal invasive or non-invasive filtering procedure, since the laser energy can be delivered via an optical fiber or slit lamp/gonio-lens technique."